1. Field of the Invention
The invention relates to a measuring method and system, more particularly to a method and system for testing liquid crystal display driver chips that utilize probability and statistics in the analysis of the accuracy of measured values and that can be realized using pin electronics (PE) cards or comparators.
2. Description of the Related Art
Due to increasing market demand of communications systems, multi-media and computer peripherals, liquid crystal displays are continuously replacing conventional Cathode Ray Tube (CRT) monitors. As a result, the demand for liquid crystal display driver chips is also increasing at a rapid pace. In the known driver chips, several hundred drive pins are integrated into a single chip to promote overall efficiency as well as to reduce chip area and costs. To test chips with a high pin count, faster and more complicated testing machines are required to meet test specifications. However, fast and highly accurate testing machines for driver chips are very expensive. Moreover, the large number of pins in a chip results in difficulty in measuring internal voltages. Therefore, the design of an economical, effective and accurate way of testing liquid crystal display driver chips is a very tough challenge.
Testing of liquid crystal display driver chips is similar to that for voltage levels. How voltages of internal nodes can be measured for debugging is a very important step. In general, higher accuracy is usually achieved by over-sampling during voltage measurements or, in the alternative, by applying relatively slow analog-to-digital (A/D) converters with noise-suppressing effects, such as Dual Slope ADC or Sigma Delta ADC, so as to meet the accuracy requirement. As such, trade-off must be made between measurement accuracy and testing time, where demand for accuracy often takes precedence over limitations of testing time. As a result, the testing time is often extended, thereby resulting in higher testing costs.